Method: Preheat oven to 200 degree C. Grease 6 muffin cups. For muffins, in a mixing bowl mix all dry ingredients. In separate bowl combine yogurt, milk and butter then stir into flour mix until smooth. Pour batter into greased muffin cups. For crumble, combine flour and brown sugar; then add butter and work with your fingertips until crumbles are formed. Top muffins with crumble and bake for 20-25 minutes or until ready.